Led illumination with reef-pi controller

figaro93 · May 16, 2019

hi guys I'm building a LED light for my new reef tank the light will be composed of 200 high brightness 3w LEDs for a total of 600w and I would like to connect it to my controller for the reef-pi lights I decided to form 13 strips from 16 LEDs and power them at 48V each driven by 1 Meanwell Ldd-350hw driver which is precisely dimmable 0-10v ...
now my questions can I control high power LEDs via the control unit even if they are powered at 48v? could you help me with the connection since the driver only has 5 wires? thank you

Ps. Image for driver in question

@Ranjib help me!

oreo54 · May 16, 2019

The dim wire is 5V (well it's really a range) PWM plus.
you common the DC power supplies neutrals, which completes the dim circuit..

1 Meanwell Ldd-350hw driver which is precisely dimmable 0-10v ...

Err.. no..2.5-6V for the signal @ 100 to 1KHz
https://www.meanwell.com/Upload/PDF/LDD-H/LDD-H-SPEC.PDF
Easiest diagram:

ALSO YOU only have about 44-45V available on the output side. Keep that in mind when adding your V(f)'s at 350mA.
SAFE side is to subtract 4V...

e.g 16 X 3 =48 V BUT you only will output 44..max.
Your diode V(f) @ 44V needs to be 2.75V (350mA) or less..assuming all are equal.

figaro93 · May 16, 2019

so you tell me that for this driver I have to add 15 leds cad? I will use 3w led okay if I send it only 2.74v? I read that they must have 3.4v each for the connection I understood perfectly and I thank you so much for helping me

oreo54 · May 16, 2019

figaro93 said:
so you tell me that for this driver I have to add 15 leds cad? I will use 3w led okay if I send it only 2.74v? I read that they must have 3.4v each for the connection I understood perfectly and I thank you so much for helping me

IF they have a voltage drop of 3.4V at 350mA and you are using a 48V power supply it goes like this:
48-4 = 44V / 3.4 = 12.9 diodes in series.. or 12..
Can't do 15 and keep the current at 350mA and if too much above they won't light at all ..

44V / 16 = 2.75 In the above chart that would mean the LED's would "draw" 300mA.
Even w/ a 350mA driver you will never get 350mA out..
and your 3w chips would only be at .825W...

ADD one more diode and they wouldn't light at all..well possibly VERY dimly.
2.55-ish is really the cutoff..
44V/17 =2.59V

figaro93 · May 17, 2019

I understand and if instead I bought the 700mA drivers always of the meanwell ldd700hw series always powered at 48v should I always do series of 12 led? thank you

oreo54 · May 17, 2019

Everything depends on the voltage demand of a string at 700mA
GENERALLY w/ Bridgelux type black boxes they are run around 550mA so really is the err "industry standard" current.
Voltage defines current
Current defines voltage..either way it's the same..
Just need to know X number of leds in series is <44V total..

Main problem w/ cheaper emitters is you really have no way of knowing what their REAL specs are..
hopefully the voltage they state is at the highest current recommended so it would always be less.
also lot to lot variation makes things even more difficult.

Unless one knows better designing around a V(f) of 4V is pretty safe all around.
so 11..............

so maybe you can see that it's almost impossible to be "specific"..

Ranjib · May 26, 2019

@figaro93 did you fix this or still need help?

figaro93 · Jun 1, 2019

sorry if I didn't answer but the drivers had to come from Germany and I'm in Italy so it's been over a week since I followed the advice given above and bought the meanwell ldd700hw drivers but as soon as I arrived I saw that they only have 5 cables or two for the current input at 48v two for the current output to power the LEDs that will be connected in series and only one output for the dimmer ... could you help me to understand how I can connect the whole to the reef-pi lighting controller?
Tanks

figaro93 · Jun 1, 2019

I forgot to add that I purchased 16 drivers and I will make 16 strips of 14 LEDs each and that I would like to connect
5 drivers for channel 1
5 drivers for channel 2
6 drivers for channel 3
for the three control unit channels

oreo54 · Jun 1, 2019

The neutral for the dim wire is by using the led output power supply and the controller power supply.
"Common grounds"
https://pbs.twimg.com/media/Cxj7xD2W8AQvR8w.jpg:large

figaro93 · Jun 1, 2019

sorry but I didn't understand ... I have a reef-pi unit with three channels and my drivers are wired and not side-by-side

figaro93 · Jun 1, 2019

I have just seen this scheme I have understood how I have to do to command the drivers I have only one question but I can use more than 3 channels with the pca9685 ??
I only used three channels as a reef guide - can I use all 16 channels? thank you

oreo54 · Jun 1, 2019

First wired or not the concept is the same..The negative side of the dc powering the reef-pi needs to be attached to the negative of the LED larger power supply..
This is for an "aduino based" unit but concept is the same..
https://www.rapidled.com/content/PDF/LDD-HW Dimmable Driver and Storm Controller Wiring.pdf

As to how many ldds can be hooked to one pwm channel is based on the mA output of the pwm out..
Meanwells only 'pull' micro-amps of current so many LDD pwm wires can be hooked to one channel IN GENERAL

Not a reef-pi guy..but most pwm channels are capable of at least 20mA so many parallel LDD's are possible..

Only "catch" is the V(out) of the PWM is either 3.3V (works w/ Ldd-h's but not some ldd-l's) or 5V which is fairly univeral.

figaro93 · Jun 1, 2019

I understand I thank you so much ... as soon as I have some free time I start to build it thanks a lot

Bigtrout · Jun 1, 2019

figaro93 said:
I have just seen this scheme I have understood how I have to do to command the drivers I have only one question but I can use more than 3 channels with the pca9685 ??
I only used three channels as a reef guide - can I use all 16 channels? thank you

And yes, you can use all 16 channels of the pca9685!

figaro93 · Jun 1, 2019

how can i use all pca9685 channels? always with the same method that I used for the three standard channels?

oreo54 · Jun 1, 2019

figaro93 said:
how can i use all pca9685 channels? always with the same method that I used for the three standard channels?

Don't ask me to explain..

It's complicated and the only thing I "think" I know is the frequency and bit rate are oddly tied together

and LDD's don't like > 1KHz frequency..(100MHz-1KHz)

figaro93 · Jun 2, 2019

ok, thanks to everyone, I will be updating soon

figaro93 · Jun 3, 2019

I just connected in this way an ldd700hw driver as in the picture or ground cable - and dimming cable soldered on a connector that connect to channel 1 I tried to dim the LEDs but I don't get results the black cable is the gnd and the green cable is connected to the dimming white I do not get results when I first obtained them with other dimmers is it not that I also have to connect the positive cable together with the dimming cable? thank you